Question

One electron and one proton of a hydrogen atom are at a distance of 2.2✕10−11m apart. What is the potential energy, in joules, of the electron in the proton’s field?

Answer 1

The electrostatic potential energy

$$E_p=k\frac{q_1q_2}{r}$$ $$E_p=9*10^9*\frac{-1.6*10^{-19}*1.6*10^{-19}}{2.2*10^{-11}}=-1.05*10^{-17}\:\rm J$$